1. Technical Field
The present invention relates in general to gas extraction in oilfield applications and, in particular, to an improved system, method and apparatus for a gas extraction device for down hole oilfield applications.
2. Description of the Related Art
The separation of gasses and liquids carried out in a well bore is common. The separation of gasses and liquids at the seabed as part of a subsea oilfield exploitation is becoming increasingly common. Separating the gas and using a high head centrifugal pump to pump the liquids vastly improves the project economics (e.g., asset net present value and recovery factor). The separation of the gas from the liquid also results in improved flow assurance. Moreover, pumping fluids that contain excessive amounts of gas can cause gas lock in a pump or can cause a pump to overheat and fail prematurely.
Currently, in a well bore, the accepted method of controlling the gas-liquid interface level is to manually control the amount of fluid produced by artificial lift, such as a down hole electric submersible pump (ESP). Generally, the ESP is installed and the production rate is set. If the pump encounters a gas lock condition, it is shut down to allow the well to recover, restarted and a new lower production rate is manually set. This is continued until the ESP is operating in a continuous and stable manner. Conversely, if the pump does not gas lock when the ESP is first installed and is operating in a stable manner, the production rate is manually increased in steps until a gas lock condition occurs. After recovery, the production rate is then reduced to the point of the last stable operation. The object is to produce the maximum fluid available from the well with the pumping equipment.
In such ESP applications, the liquid travels through production tubing to the surface. Excess gas gathers at the top of the well within the casing and is typically vented at the well head to a separate gathering system. Alternatively, the gas is connected into the liquid production line down stream of the wellhead. In some cases, however, production would benefit from gas entering the liquid production stream down hole within the well casing.